const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/xm',{
    useNewUrlParser: true,
    useUnifiedTopology: true
});
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
    // we're conected!
    console.log('mongodb已连接')
});